Small Craft Advisory 157, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
300 PM AST MON FEB 12 2007

.DISCUSSION...THE JET STREAM REMAINS WELL SOUTH OF THE FORECAST AREA
WHICH WILL KEEP THE STRONGEST DYNAMICS AWAY FROM THE AREA AS WELL.
THERE ARE ENOUGH DYNAMICS HOWEVER TO BRING A LOW IN HE MID 980 MB
RANGE INTO THE GULF OF ALASKA TONIGHT. THIS LOW WILL BRING GALES TO A
NUMBER OF THE MARINE AREAS AROUND THE GULF AND RAIN AND SNOW TO GULF
COASTAL AREAS. SINCE THIS LOW DOES NOT HAVE THE UPPER LEVEL SUPPORT
OF THE JET STREAM IT WILL FADE FAIRLY QUICKLY IN THE NORTHWEST GULF
AND DISSIPATE WEDNESDAY MORNING. AN ADDITIONAL FACTOR THAT WILL KEEP
THE LOW FROM MOVING ONSHORE IS A LARGE RIDGE IN CANADA. THOUGH THIS
RIDGE IS OVER THE NORTHWEST TERRITORIES IT IS UP TO 1047 MB AND WILL
KEEP THE GULF LOW FROM PROGRESSING.

THE UPPER LEVEL PATTERN TOWARD THE WESTERN PART OF THE STATE HAS A
LOW OVER THE CENTRAL BERING SEA WITH TROUGH EXTENDING TOWARD THE LOW
IN THE GULF. THIS IS CAUSING MOIST SOUTHEAST FLOW OVER THE BRISTOL
BAY AREA AND WILL HELP THE SNOW SHOWERS TO PERSIST IN THAT AREA.

THERE REMAINS A WEAK SURFACE LOW IN THE CENTRAL BERING SEA. THIS LOW
WILL PERSIST FOR A WHILE AS IT DRIFTS NORTH OF SHEMYA TUESDAY AND
THEN GETS PULLED BACK TO THE SOUTHEAST WEDNESDAY AS ANOTHER LOW
DEVELOPS SOUTH OF THE CENTRAL ALEUTIAN ISLANDS.

MODELS HAVE THE SAME GENERAL IDEA BUT THERE ARE SOME DIFFERENCES THAT
ONE SHOULD BE AWARE OF. THE MAIN DIFFERENCE IS ON THE LOW IN THE
GULF. THE GFS DISSIPATES THE LOW TUESDAY EVENING IN THE NORTHWEST
GULF WHILE THE NAM HOLDS THE LOW IN POSITION IN THE NORTHWEST GULF
THROUGH WEDNESDAY AFTERNOON. PREFER THE GFS SOLUTION SINCE THE
THERMAL GRADIENT DOES NOT SUPPORT THIS LOW SURVIVING INTO WEDNESDAY.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 120 130 132 138 150.
FIRE WEATHER...NONE.

FEB 07